Multi-layer rigid prototype fabrication requires special techniques. Generally, multi-layer rigid circuit board prototype fabrication involves drilling a board-hole pattern via a NC driller where the hole sizes are determined by the size of the pins effecting inter-layer connections at particular holes. Dry sheet adhesive is then applied to the proper side of each circuit layer produced by a plotter/etcher. Such plotter/etcher created circuit layer, maybe effected by a computer aided-etcher as set forth in U.S Pat. No. 4,767,489 issued Aug. 30, 1988 to co-applicant Frederick H. Linder, and assigned to the common corporate assignee.
The layers are then prepared and laminated to each side of a rigid substrate. Post drilling of the laminated assembly is the next step along with routing out the board outline using such NC driller. The prototype PC board is finished by installing pins or connectors in the appropriate holes from the components side. This may involve populating the Board with components and soldering as a final step before testing the design.
While the computer aided printer-etcher greatly facilitates the manufacture of a multi-layer rigid prototype printed circuit board and while, U.S. Pat. No. 4,767,489 states that the techniques in further treating the printed circuit film 19 after passage through the printer-etcher unit of that patent, are conventional such is true for double-sided printed circuit boards. However, in order to apply the printer-etcher to producing a prototype or experimental multi-layer printed circuit board, inter-connection of the multiple conductor tracks of the stacked layers utilizing prior art techniques are tedious, complex and time consuming.
It is therefore primary object of the present invention to accomplish the inter-connection between conductor tracks of multiple layers of a double-sided prototype printed circuit board by electroless tin plating and utilizing uniquely designed, exterior shaped through hole pins having several sharp corners for physical distortion of the thin flexible films to accomplish by pin penetration, the required multi-layer track inter-connections.